There are numerous ways to control the incoming traffic to a specific user. We can

1.Transport Rules,

2.Recipient Filtering,

3.Change at mailbox level

How to configure Transport Rules for controlling Incoming traffic

Transport Rules feature allows administrators to create a rule to return a NDR to the sender, for example, saying that this specific user does not have permission to receive Internet mail. This can be done as follows:

Open Exchange Management Console

Expand Organization Configuration

Click on Hub Transport

Click on Transport rules tab

On Toolbox Actions or in white area, right click and select New Transport Rule

6. In the Introduction page, enter any Name for the rule, enter Comment and click Next

7. In the Conditions page. Select the from users inside or outside the organization item and sent to people item as well. Make sure that the Outside value is selected for the first one and for the second one select the user mailbox that will not be able to receive Internet mail. Click Next once done.

Recipient Filtering anti-spam agent is enabled by default in an Edge Transport Server. However, if you are using the Hub Transport role to receive internet mail you need to enable the Anti-Spam Transport Agents.

Either way, the process to configure the Recipient Filtering is very similar. Let us see how we can configure Recipient Filtering in a Hub Transport.

Open Exchange Management Console.

Expand Organization Configuration.

Click on Hub Transport.

Click on Anti-spam tab.

Open the Properties of Recipient filtering.

6. Click on Blocked Recipients tab.

7. Enter the address of internal user that you may want to block for receiving internet emails

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The result, as you may expect, is that any message sent from the Internet to
This email address is being protected from spambots. You need JavaScript enabled to view it.
will return a NDR saying that the user does not exist in our organization.

How to Configure Mail Receiving Restrictions on Mailbox level

Well, sometimes blocking external incoming traffic to a user is not enough and you want to make the restriction a little tighter. Restricting a user to only receive messages from his boss and no other email client is one such example.

The configuration process is as follows:

Open Exchange Management Console

Expand Recipient Configuration

Click on Mailbox

Open the Properties of the mailbox that you want to restrict

.

5. Click on Mail flow settings tab

6. Click on Message Delivery Restriction and click on Properties

7. On this page, we are able to restrict the user to accept or reject message from specific users. This user can only accept messages from authenticated users.